In today's information age, communication networks are often used for interconnecting computers and computer peripherals. A communication network typically includes a number of nodes that interoperate to route protocol messages. The various nodes in the communication network utilize various routing protocols in order to determine the routes that are used to route the protocol messages.
One type of routing protocol, known as a “link state” routing protocol, determines routes based upon the status of communication links between the various nodes. A link state routing protocol, such as the Open Shortest Path First (OSPF) routing protocol, requires each node to have complete topology information. Each node maintains a topology database that indicates all nodes in the communication network and lists the communication links that are associated with each node.
The various nodes in the communication network exchange link state information using link state advertisement (LSA) protocol messages. Link state information is exchanged at various times. In particular, when a node is initialized, the node needs to obtain link state information in order to determine routes for routing protocol messages, and therefore the node's neighbors send LSA protocol messages to the node in order to provide the node with the necessary link state information. Also, each node periodically tests the communication links to each of its neighbors and sends a LSA protocol message including the link status information to all of the other nodes. When a failure occurs in the communication network (such as a communication link failure or a node failure), the various nodes in the communication network need to obtain updated link state information in order to determine new routes for routing protocol messages around the failure, and therefore the nodes adjacent to the failure send LSA protocol messages to the other nodes in the communication network in order to inform all nodes of the failure. Each node computes the routes based upon the link status information received from the other nodes.
Any time link state information is exchanged, it is desirable for the link state information to be distributed quickly in order for the receiving node(s) to determine new routes for routing protocol messages. Unfortunately, routing protocols utilize a “stop-and-wait” mechanism for distributing link state information. When a node sends an LSA protocol message to a neighbor, the node waits for an acknowledgment from the neighbor before sending another ISA protocol message. This is a very simple but inefficient way to distribute link state information.
An efficient technique for distributing link state information is needed.